George blanobard



o 0 M P A S S N E E D L El No. 332,780. Patented Dec.122, 1885.

i UNITED STATES GEORGE BLANOH ARD,

PATENT OFFICE.

OF NEV YORK, N. Y.

COMPASS-NEEDLE.

SPECIFICATION forming part of Letters Patent No. 332,780, dated December22, 1885.

Application filed October 13, 1883. Serial No. 108,937. (Model.)

To all whom, it may concern:

Beit known that I, GEORGE BLANCHARD, a citizen of the United States,residing at New York, county and State of New York, have invented a newand useful Improvement in Needles for Compasses, of which the followingis a specification.

It is well known that the best of mariners compasses are subject tooscillation and variation by reason of local attraction and electricstorms, as well as by both celestial and terrestrial magnetism. Theseinfluences are so powerful that frequently magnetic needles have beenknown to change entirely their polarity, rendering them utterly uselessand even dangerous. The whole world knows too well the evil results inthe loss of many a ship with all her cargo, passengers, and crew.

To remedy these evils is the object of my invention, which consists,broadly, in a magnetic needle which is attracted by but one of themagnetic poles. I make two needles, one of which is a north needleexclusively. The other is a south needle exclusively.

Referring to the drawings making a part of this specication, Figures land 2 are both under side views of compass-cards with my improvedneedles attached thereto. Fig. 1 illustrates the north needle and Fig. 2the south needle.

C represents the ordinary compasscard, with the cardinal points of thecompass denoted, as usual, by the letters N, S, E, and W. Thenorth-pointing needle, Fig. l, is denoted by A, and the south-pointingneedle, Fig. 2, by B.

D is a weight, attached adjustably in a slot of the extendednon-magnetic end opposite to the needle. The adjustment of this weightto balance the needle is old.

To enable others skilled in the art to make and use my invention, itsstructure is as follows:

I magnetize a piece of steel, and I fasten this upon the dial leadingfrom the pivot to the perimeter of one side of the dial onlythat is, theneedle in my compass is mounted radially on the card. To make anorth-pointing needle I place the positive end at the edge of the dialand the negative at the pivot. To make a south-pointing needle I reversethis,

or apply the negative end of the needle to the perimeter of the card,and the positive end of the needle at the pivot. I hereby have thestrongest polar grip upon my needle, thereby giving the greateststability and the very least of oscillation or variation; and Icounteract or do away with at least from fty to seventyfive per cent. ofall local attraction Without interfering with desired polar attraction,but rather rendering it decidedly stronger. This can be demonstrated bypowerful horseshoemagnets, which, when brought into proximity with thebest mariners compasses now known on shipboard, or anywhere to be foundon sale by nautical-instrument dealers, cause the needles in them tooscillate just as electric storms cause them to, and this occurs whetherthe magnets be passed over them in the direction of their lengths or atright angles thereto, or be passed around them in either direction, witheither a slow or rapid motion; but when thus applied to my improvedneedles they have no perceptible effect.

My needles have seventy-five per cent. advantage over all the bestCompasses known in maritime circles in doing away with local attraction.v

To counterpoisc my needle I attach an adjustable weight to the oppositeside of the compass-card, as shown at D.

To make a compass for miners7 or surveyors7 purposes, my needle may beapplied to a piece of light wood or any other suitable material,A andmounted on any pivot, weighting the light wood at the opposite end tocounterpoise the needle.

A great advantage in using Compasses having my needles is that wherethere might be a doubt as to the true bearing, my two compasses are atest one of the other. Suppose my two compasses to be mounted, say, vefeet, more or less apart on the ship. By reference to them the needleswill be found parallel.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is-

l. A compass-card having amagnetic needle radially attached theretoWholly to one side of the pivot, as and for the purpose described.

2. The combination, in a mariners or sur;

veyors compass, of a compasscard suitably 4. A magnetic needle, incombination with pivoted, with a compass-needle radially afacoinpasscard, upon which the said needle is xed thereon and Wholly toone side of the radially attached Wholly at one side of the pivot,substantially as described. pivot, and a suitable counterpoise, as andfor 5 3. The combination of an ordinary compass-l the purpose set forth.

card or other suitable supporting material, l;

and a magnetic needle radially ai'ixed thereto i GEORGE BLANCHARD. andwholly to one side of the pivot of said Vitnesses: compass-card orsupporting material, as and DENIS KEENAN,

1o for the purpose set forth. W. B. READ.

